In an electrical utility grid, consumers can usually consume electric power in an uncontrolled manner. Since hardly any energy is stored in the grid, there can be no imbalance between the power produced and the power consumed. Therefore, the momentary production of power shall match the momentary power consumption. Overproduction leads to an increase of the grid frequency beyond the nominal value (e.g. 50 or 60 Hz), since the conventional synchronous generators accelerate, while over consumption will lead to a decrease of the grid frequency beyond the nominal value (e.g. 50 or 60 Hz), since the conventional synchronous generators will then decelerate.
In order to stabilize the frequency of the electrical grid, conventionally about 10% of the producers contribute to what is called “primary power control”. These producers, also referred to as “primary controllers”, increase power output when the frequency falls below the nominal value and decrease power output when it rises above the nominal value.
Wind turbine generators (WTG) can be used to provide energy to the electrical utility grid. Wind turbine generators are sometimes referred to as wind turbines (WT). A plurality of WTGs can form a wind power plant (WPP) also known as a wind park or a wind farm.
A Power Plant Controller (PPC), which operates as a wind power plant (WPP) controller, generates proper active power set-points to all WTGs, in order to allow the plant active power follow certain active power reference on the plant level. The part of the PPC which generates the active power set-points to all WTGs is called a dispatcher. The dispatcher coordinates all kinds of control modes, for instance, frequency control mode, active power curtailment mode, active power fast de-rating control mode, and so on.
It is thus highly relevant to provide a method for controlling a wind power plant in a manner which ensures improved control modes by selecting and dispatching proper active power reference to a plurality of wind turbine generators in a WPP, so the aggregated active power of the power plant match the active power reference. Furthermore, it is relevant to provide a wind power plant which reacts fast to changes in the requested active power.